Blender using memory for no reason; Blender loading up Memory Usage. Why is that?
Basically the problem you're facing is that blender is storing a large amount of memory for the undo steps.

You can change this by going to File -> user preferences, under the Editing tab you'll find a section called Undo.
Here you can adjust the number of undo steps and memory limit.
The lower the amount of undo steps, the less memory blender will have to store.

That's why repeatedly clicking on random operators is clearing your memory stored in previous computationally expensive undo steps.